Org reader: support macros

Closes: #3401

3 files changed, 65 insertions, 1 deletions

diff --git a/src/Text/Pandoc/Readers/Org/Inlines.hs b/src/Text/Pandoc/Readers/Org/Inlines.hs
index 64ffb8ef5..5772e4157 100644
--- a/src/Text/Pandoc/Readers/Org/Inlines.hs
+++ b/src/Text/Pandoc/Readers/Org/Inlines.hs
@@ -120,6 +120,7 @@ inline =
          , superscript
          , inlineLaTeX
          , exportSnippet
+         , macro
          , smart
          , symbol
          ] <* (guard =<< newlinesCountWithinLimits)
@@ -839,6 +840,26 @@ exportSnippet = try $ do
   snippet <- manyTill anyChar (try $ string "@@")
   returnF $ B.rawInline format snippet
 
+macro :: PandocMonad m => OrgParser m (F Inlines)
+macro = try $ do
+  recursionDepth <- orgStateMacroDepth <$> getState
+  guard $ recursionDepth < 15
+  string "{{{"
+  name <- many alphaNum
+  args <- ([] <$ string "}}}")
+          <|> char '(' *> argument `sepBy` char ',' <* eoa
+  expander <- lookupMacro name <$> getState
+  case expander of
+    Nothing -> mzero
+    Just fn -> do
+      updateState $ \s -> s { orgStateMacroDepth = recursionDepth + 1 }
+      res <- parseFromString (mconcat <$> many inline) $ fn args
+      updateState $ \s -> s { orgStateMacroDepth = recursionDepth }
+      return res
+ where
+  argument = many $ notFollowedBy eoa *> noneOf ","
+  eoa = string ")}}}"
+
 smart :: PandocMonad m => OrgParser m (F Inlines)
 smart = do
   guardEnabled Ext_smart
diff --git a/src/Text/Pandoc/Readers/Org/Meta.hs b/src/Text/Pandoc/Readers/Org/Meta.hs
index 7938fc6c6..8c362f209 100644
--- a/src/Text/Pandoc/Readers/Org/Meta.hs
+++ b/src/Text/Pandoc/Readers/Org/Meta.hs
@@ -46,7 +46,7 @@ import Text.Pandoc.Definition
 
 import Control.Monad (mzero, void)
 import Data.Char (toLower)
-import Data.List (intersperse)
+import Data.List (intersperse, sort)
 import qualified Data.Map as M
 import Network.HTTP (urlEncode)
 
@@ -151,6 +151,7 @@ optionLine = try $ do
     "todo"     -> todoSequence >>= updateState . registerTodoSequence
     "seq_todo" -> todoSequence >>= updateState . registerTodoSequence
     "typ_todo" -> todoSequence >>= updateState . registerTodoSequence
+    "macro"    -> macroDefinition >>= updateState . registerMacro
     _          -> mzero
 
 addLinkFormat :: Monad m => String
@@ -218,3 +219,27 @@ todoSequence = try $ do
      let todoMarkers = map (TodoMarker Todo) todo
          doneMarkers = map (TodoMarker Done) done
      in todoMarkers ++ doneMarkers
+
+macroDefinition :: Monad m => OrgParser m (String, [String] -> String)
+macroDefinition = try $ do
+  macroName <- many1 nonspaceChar <* skipSpaces
+  firstPart <- expansionPart
+  (elemOrder, parts) <- unzip <$> many ((,) <$> placeholder <*> expansionPart)
+  let expander = mconcat . alternate (firstPart:parts) . reorder elemOrder
+  return (macroName, expander)
+ where
+  placeholder :: Monad m => OrgParser m Int
+  placeholder = try . fmap read $ char '$' *> many1 digit
+
+  expansionPart :: Monad m => OrgParser m String
+  expansionPart = try $ many (notFollowedBy placeholder *> noneOf "\n\r")
+
+  alternate :: [a] -> [a] -> [a]
+  alternate [] ys = ys
+  alternate xs [] = xs
+  alternate (x:xs) (y:ys) = x : y : alternate xs ys
+
+  reorder :: [Int] -> [String] -> [String]
+  reorder perm xs =
+    let element n = take 1 $ drop (n - 1) xs
+    in concatMap element perm
diff --git a/src/Text/Pandoc/Readers/Org/ParserState.hs b/src/Text/Pandoc/Readers/Org/ParserState.hs
index bdd1dc951..e47565814 100644
--- a/src/Text/Pandoc/Readers/Org/ParserState.hs
+++ b/src/Text/Pandoc/Readers/Org/ParserState.hs
@@ -39,6 +39,9 @@ module Text.Pandoc.Readers.Org.ParserState
   , TodoState (..)
   , activeTodoMarkers
   , registerTodoSequence
+  , MacroExpander
+  , lookupMacro
+  , registerMacro
   , F
   , askF
   , asksF
@@ -78,6 +81,8 @@ type OrgNoteTable = [OrgNoteRecord]
 -- | Map of functions for link transformations.  The map key is refers to the
 -- link-type, the corresponding function transforms the given link string.
 type OrgLinkFormatters = M.Map String (String -> String)
+-- | Macro expander function
+type MacroExpander = [String] -> String
 
 -- | The states in which a todo item can be
 data TodoState = Todo | Done
@@ -105,6 +110,8 @@ data OrgParserState = OrgParserState
   , orgStateLastPreCharPos       :: Maybe SourcePos
   , orgStateLastStrPos           :: Maybe SourcePos
   , orgStateLinkFormatters       :: OrgLinkFormatters
+  , orgStateMacros               :: M.Map String MacroExpander
+  , orgStateMacroDepth           :: Int
   , orgStateMeta                 :: F Meta
   , orgStateNotes'               :: OrgNoteTable
   , orgStateOptions              :: ReaderOptions
@@ -156,6 +163,8 @@ defaultOrgParserState = OrgParserState
   , orgStateLastPreCharPos = Nothing
   , orgStateLastStrPos = Nothing
   , orgStateLinkFormatters = M.empty
+  , orgStateMacros = M.empty
+  , orgStateMacroDepth = 0
   , orgStateMeta = return nullMeta
   , orgStateNotes' = []
   , orgStateOptions = def
@@ -185,6 +194,15 @@ activeTodoSequences st =
 activeTodoMarkers :: OrgParserState -> TodoSequence
 activeTodoMarkers = concat . activeTodoSequences
 
+lookupMacro :: String -> OrgParserState -> Maybe MacroExpander
+lookupMacro macroName = M.lookup macroName . orgStateMacros
+
+registerMacro :: (String, MacroExpander) -> OrgParserState -> OrgParserState
+registerMacro (name, expander) st =
+  let curMacros = orgStateMacros st
+  in st{ orgStateMacros = M.insert name expander curMacros }
+
+
 
 --
 -- Export Settings